Silicone multiple bonds

Recent advances in the chemistry of silicon-silicon multiple bonds... 

Silicon-silicon multiple bonds with a bond order greater than two are still unknown. According to theoretical calculations, voluminous and concomitantly electropositive substituents are the most promising candidates with the potential to stabilize disilynes having a formal Si Si triple bond. When and by what synthetic route this challenge for experimental chemistry will be realized is a question that only time can answer. 

Finally, the rapid developments in recent years led to chapters which are updates of those in Vol. 2. These include recent developments in the chemistry of silyl radicals, of silicon-silicon multiple bonds and of silicon-nitrogen bonds. 

Compound 7 crystallizes in the monoclinic space group P2 ln, and shows a pseudo-tetrahedral geometry around the silicon atom. One notable feature of 7 is the short Crl-Sil interatomic distance of 2.385(1) A, which corresponds to those found in other chromium-silicon multiple bond systems [9, 12]. In addition, the Sil-Nl interatomic distance of 1.954(2) A is shorter than that found in hypervalent DMBA- substituted aryl- [12], alkyl-, and vinyl-dichlorosilanes [13]. This is in agreement with the high electrophilicity of the silicon atom in 7. 

New Molecular Systems with Silicon-Silicon Multiple Bonds... 

New Molecular Systems with Silicorr-Silicon Multiple Bonds 27... 

Summary This conttibution describes two general approaches to the development of new transition metal-based silicon chemistry. In one approach, the focus is on early transition metals and the chemistry of d metal-silicon bonds. A second approach targets metal-silicon multiple bonds, which are expected to exhibit rich reaction chemistry. Various new compounds and chemical processes are discussed. 

Multiple bonds involving the lightest member of group 14 are ubiquitous (i.e. alkenes and alkynes) and traditional chemical bonding theories such as Valence Bond Theory can adequately describe such interactions. The chemistry of compounds containing silicon-silicon multiple bonds, disilenes, and disilynes has not developed in parallel with that of carbon. Nonetheless, significant advances have recently been made, most prominently the report of the first example of a -Si=Si- triple bond. 

---